The present invention relates to a control device for a breaker.
In operating a breaker as a make break switch, a control device utilizing a spring force has been practiced.
FIGS. 25 to 31 show a conventional control device for a breaker disclosed in, for instance, JP-A-63-304542. FIG. 25 is a perspective view showing the A construction of such control device for a breaker. FIG. 26 is a diagram showing an important portion of the control device of the breaker, wherein the breaker is in a state of closing the circuit, and both opening and closing torsion bars are prestressed.
FIG. 27 is a diagram showing a making electromagnet and elements related to the making electromagnet. FIG. 28 is a diagram showing the important portion of the control device of the breaker in a opening state, wherein the opening torsion bars are released and the closing torsion bars are prestressed. FIG. 29 is a diagram showing the important portion of the control device of the breaker in a closing state, wherein the opening torsion bars are prestressed and the closing torsion bars are released. FIG. 30 is a sequential diagram of a control circuit in the breaker, and FIG. 31 is a diagram showing an operation chart of an auxiliary switch.
In these figures, numerical reference 1 designates a casing, numerical reference 24 designates a cylinder fixed to the casing 1, and numerical references 26 and 27 designate levers fitted to pins (not shown) provided at an end face of the cylinder 24 so as to be capable of rotating. Numerical references 28 and 34 designate opening torsion bars, and numerical references 29 and 35 designate closing torsion bars. In order to prestress the opening torsion bars 28 and 34 by releasing the A closing torsion bars 29 and 35, energy stored by the closing torsion bars 29, 35 is made larger than energy stored by the opening torsion bars 28, 34. The opening torsion bar 28 has an end fixed to the casing 1 and the other end fixed to the lever 26. The opening torsion bar 34 has an end fixed to a rotating shaft 32 and the other end fixed to the lever 26.
The closing torsion bar 29 has an end fixed to the casing 1 and the ether end fixed to the lever 27. The closing torsion bar 35 has an end fixed to a rotating shaft 33 and the other end fixed to the lever 27. Numerical reference 37 designates a making lever fixed to the rotating shaft 33, which is so constructed that a rotating force in a counterclockwise direction in FIG. 26 is given by the closing torsion bars 29, 35. In this text, indications concerning a rotational direction, left and right directions and upper and lower directions are based on the surface of papers on which the figures are drawn unless specifically mentioned. Numerical reference 2 designates a camshaft supported by the casing 1; numerical reference 3 a cam attached to the cam shaft 2; numerical reference 13 a second pin formed in the cam 3, and numerical reference 14 a making latch engaged with the second pin 13. Numerical reference 15 designates a making trigger engaged with the making latch 14, which is provided with a head portion 15a and a corner edge portion 15b. 
Numerical reference 16 designates a making electromagnet which has a making coil 16a and a plunger 16b as shown in detail in FIG. 27. The plunger 16b comprises a body portion 16c and a trigger lever 16d connected rotatably to the body portion 16c by means of a pin 16f. The trigger lever 16d has a stepped portion 16e so as to be capable of engaging with the making trigger 15. Numerical reference 17 designates a spring to urge the trigger lever 16d in a clockwise direction so that the trigger lever 16d is held in a horizontal state in contact with a stopper (not shown) formed in the body portion 16c. 
Numerical reference 21 designates a leaf spring attached to the casing 1 so as to oppose to the trigger lever 16d wherein an upper portion of the leaf spring is free with respect to the casing, and it is deformable elastically in left and right directions in FIG. 27. The plunger 16b is driven in a right direction in FIG. 27 when the making coil 16a is excited. When excitation to the making coil 16a is stopped, it is returned to the original position by the action of a return spring (not shown).
In FIG. 26, numerical reference 38 designates a Us rotating shaft supported by the casing 1 and is driven by a motor (not shown) in a counterclockwise direction. Numerical reference 39 designates a pinion fixed to the rotating shaft 38 and numerical reference 40 designates a gear which is fixed to the camshaft 2 to mesh with the pinion 39 and in which a part of the teeth is removed so that it disengages from the pinion 39 when the closing torsion bars 29, 35 are prestressed. Numerical reference 41 designates a link connecting a making lever 37 with the gear 40.
Numerical reference 36 designates a breaking lever fixed to the rotating shaft 32 and is so constructed as to receive a rotating force in a counterclockwise direction by the opening torsion bars 28, 34. Numerical references 8 and 9 designate respectively a first pin and a rotor attached to the breaking lever 36. Numerical reference 18 designates a releasing latch which is engaged with the first pin 8 and receives a rotating force in a clockwise direction by a spring 43.
Numerical reference 19 designates a releasing trigger engaged with the releasing latch 18 and numerical reference 20 designates a releasing electromagnet having a releasing coil 20a and a plunger 20b. The plunger 20b is driven in a right direction in FIG. 26 by the excitation to the releasing coil 20a. When excitation to the releasing coil 20a is stopped, the plunger 20b is returned to the original position by the action of a return spring (not shown). Numerical reference 10 designates an on-off contact of the breaker, numerical reference 12 a stationary contact and numerical reference 22 a movable contact. The movable contact 22 is connected to the breaking lever 36 via a linkage mechanism 23. Numerical reference 42 designates a buffer connected to the breaking lever 36 to relax an impact applied at the time of on-off operations of the movable contact 22.
In the next, the operation of opening the circuit will be described. In FIG. 26, the breaking lever 36 is constantly applied with a rotating force in a counterclockwise direction by the opening torsion bars 28, 34, and the rotating force is retained by the releasing latch 18 and the releasing trigger 19. When the releasing electromagnet 20 is excited in this state, the plunger 20b is moved in a right direction and the releasing trigger 19 is rotated in a clockwise direction whereby the releasing latch 18 is rotated in a counterclockwise direction by a counter force applied from the first pin 8. When the releasing latch 18 is disengaged from the first pin 8, the breaking lever 36 is rotated in a counterclockwise direction, and the movable contact 22 is driven in a direction of opening the circuit. FIG. 28 shows a state that the operation of opening the circuit is completed.
An operation of closing the circuit is conducted as follows. In FIG. 28, the cam 3 is connected to the making lever 37 via the camshaft 2, the gear 40 and the link 41, wherein a rotating force in a clockwise direction is applied by the closing torsion bars 29, 35. The rotating force is retained by the making latch 14 and the making trigger 15.
When the making electromagnet 16 is excited in this state, the body portion 16c of the plunger 16b and the trigger lever 16d connected thereto are moved in a right direction, and the making trigger 15 is rotated in a clockwise direction by a kicking motion thereof, whereby the making latch 14 is rotated in a counterclockwise direction by a counter force from the second pin 13. When the making latch 14 is disengaged from the second pin 13, the cam 3 is rotated in a clockwise direction, and the rotor 9 mounted on the breaking lever 36 is pushed up, whereby the breaking lever 36 is driven by twisting the opening torsion bars 28, 34 in a clockwise direction.
Further, the making latch 14 is disengaged from the making trigger 15 to rotate in a counterclockwise direction, and the making trigger 15 is further rotated in a clockwise direction by a pushing force of the making latch 14. At this moment, since the corner edge portion 15b of the making trigger 15(FIG. 27) pushes up the trigger lever 16d, and the trigger lever 15 is urged in a right direction by the excitation to the coil 16a, the trigger lever 16d rides on the leaf spring 21. Since the trigger lever rides on the leaf spring 21 in the completion of closing the circuit, the making trigger 15 is returned to a self-standing position without any interference by the trigger lever 16d, whereby the engagement of the making latch 14 with the making trigger becomes possible, and the closing torsion bars 29, 35 are ready for a prestressed state.
When the excitation to the making electromagnet 16 is stopped, the plunger 16d is moved for returning in a left direction by a return spring (not shown). By the returning in the left direction of the plunger 16d, the trigger lever 16d is disengaged from the leaf spring 21 and is pushed by the spring 17 to become a horizontal state. Thus, the control device is returned to the state as shown in FIG. 28.
The closing torsion bars 29, 35, after having been released, are immediately prestressed by the motor via the pinion 39 and the gear 40, and the second pin 13 is retained by the making trigger 15, which is returned to the self-standing position, by means of the making latch 14, whereby the closing torsion bars are kept to a prestressed state.
As describe above, the closing torsion bars 29, 35 can be kept in a prestressed state even though the making electromagnet 20 is in excitation, and the circuit closing operation by the on-off contact 10 is prevented even when the closing torsion bars 29, 35 are released again. Namely, the rotation of the making trigger 15 by the trigger lever 16d can not be effected unless the excitation to the making electromagnet 16 is stopped, so that the on-off contact 10 can not close the circuit. Thus, the pumping is mechanically suppressed.
When the breaking lever 36 is rotated by a predetermined angle and the movable contact 22 is driven in the direction of closing the circuit, the releasing latch 18 is engaged with the first pin 8, and the releasing trigger 19 is engaged with the releasing latch 18. The cam 3 is continuously rotated to hold the breaking lever 36 via the rotor 9 until the engagement between the releasing latch 18 and the first pin 8 and between the releasing trigger 19 and the releasing latch 18 are stabilized. Thereafter, the cam 3 is disconnected from the rotor 9. FIG. 29 shows a state that the operation of closing the circuit is completed, and the first pin 8 is retained by the releasing latch 18.
The operation of prestressing the closing torsion bars 29, 35 is as follows. As shown in FIG. 29, immediately after the completion of closing the circuit, the closing torsion bars 29, 35 are in a releasing state. By rotating the pinion 39 in the counterclockwise direction by the motor (not shown), the gear 40 is rotated in the clockwise direction, and the closing torsion bars 29, 35 are prestressed via the link 41, the making lever 37 and the rotating shaft 33.
At the position of dead point where a direction of pulling the link 41 crosses the center of the camshaft 2, the camshaft 2 is applied with a rotating force in a clockwise direction through the link 41 by the force of the closing torsion bars 29, 35. At the same time, the engagement between the pinion 39 and the gear 40 is released because the teeth of the gear 40 are partly removed. The making latch 14 is engaged with the second pin 13, and the rotating force of the gear 40 in the clockwise direction caused by the force of the closing torsion bars 29, 35 is retained, whereby the prestressing operation is completed. Thereafter, the control device is returned to the state as shown in FIG. 26.
Next, the operational sequence of the breaker is explained with reference to FIG. 30. In FIG. 30, numerical reference 52C represents a making coil 16a of the making electromagnet 16 and numerical reference 52T represents a releasing coil 20a of the releasing electromagnet 20. Numerical references 52a, 52b designate respectively a normally open contact and a normally close contact of an auxiliary switch (not shown) of the breaker. Numerical reference 881a designates a normally open contact of a circuit closing auxiliary relay (not shown) for generating a circuit closing instruction and numerical reference 882a designates a normally open contact of a circuit opening auxiliary relay (not shown) for generating a circuit opening instruction.
The making coil 52C has a terminal at one side which is connected to a negative terminal N of a D.C. power source and the other terminal at the other side which is connected to a positive terminal P of the D.C. power source through the normally close contact 52b, the making terminal C and the normally open contact 881a. The releasing coil 52T has a terminal at one side which is connected to the negative terminal N of the D.C. power source and the other terminal at the other side which is connected to the positive terminal P of the D.C. power source through the normally open contact 52a, the releasing terminal T and the normally open contact 882a. 
The auxiliary switch of the breaker is mechanically connected to the breaking lever 36 to open and close the normally open contact 52a and the normally close contact 52b in connection with the opening/closing of the on-off contact 10 for opening and closing the main circuit of the breaker. Further, the auxiliary switch is so adapted that in an operation of closing the circuit of the breaker, the normally close contact 52b is opened at a point P1 at a time point t1 in a change of the stroke of the movable contact 12, and the normally open contact 52a is closed at a point P2 at a time point t2, whereby the releasing coil 52T can be excited, as shown in the operational chart of FIG. 31.
Further, in an operation of opening, the normally open contact 52a is opened at a point P3 at a time point t3 in the course of opening the circuit, whereby the excitation to the releasing coil 52T is stopped. Further, at a point P4 at a time point t4, the normally close contact 52b is closed, and the excitation to the making coil 52C becomes possible.
Since a circuit opening instruction is generated continuously in the above-mentioned conventional control device for breakers, the normally close contact 52b is closed at the point P4, in FIG. 31, in the course of opening the circuit even when the normally open contact 882a is closed in FIG. 30, and accordingly, the excitation to the making coil 52C (16a) becomes possible. In such state, when the normally open contact 881a (FIG. 30) is closed by a circuit closing instruction, the making coil 52C is excited thereby conducting a circuit closing operation. Further, a circuit closing operation is made even by exciting the making coil 52C manually.
Although electrically interlocking means are provided in a control circuit for breakers so as not to generate a circuit closing instruction while a circuit opening instruction is generated, there is still a possibility to cause a circuit closing operation while the circuit opening instruction is generated. Therefore, there is a demand of eliminating certainly such disadvantage so that reliability on keeping a circuit opening state can be increased.
It is an object of the present invention to provide a control device for a breaker, which prevents an undesired circuit closing operation and improves the reliability on keeping a circuit opening state.
According to an aspect of the present invention, there is provided a control device for a make break switch which comprises a prestressing means for opening circuit, connected to an on-off contact; a retaining means for opening circuit, which retains a prestressing force of the prestressing means for opening circuit and which according to a circuit opening instruction, releases the prestressing force of the prestressing means for opening circuit to open the on-off contact by a releasing force of the prestressing means for opening circuit; a retaining means for closing circuit, which retains a prestressing force of a prestressing means for closing circuit and which according to a circuit closing instruction, release the prestressing force of the prestressing means for closing circuit to close the onoff contact by a releasing force of the prestressing means for closing circuit via the prestressing means for opening circuit; and a making operation preventing device actuated by an circuit opening instruction to prevent the releasing of the prestressing force of the prestressing means for closing circuit, which is caused by the retaining means for closing circuit.
Since the making operation preventing device is so adapted as to receive a circuit opening instruction to thereby prevent the releasing of the prestressing force of the prestressing means for closing circuit, which is caused by the retaining means for closing circuit, a needless circuit closing operation can be prevented when the circuit opening instruction is generated.
Further, the retaining means for closing circuit comprises a circuit closing electromagnet having a plunger which is driven by an exciting coil and a releasing member driven by the plunger to release the prestressing force of the prestressing means for closing circuit, and the making operation preventing device is provided to prevent the releasing member from being driven by the plunger.
Since the releasing member can not be driven by the plunger, a needless circuit closing operation can be prevented when a circuit opening instruction is generated.
Further, in the retaining means for closing circuit, the plunger has a body portion and a rotatable member connected to the body portion so as to be capable of being bent by rotating itself in a direction perpendicular to the direction of moving the body portion, said retaining means for closing circuit being adapted to release the prestressing force of the prestressing means for closing circuit by driving the releasing means via the rotatable member, and the making operation preventing device has an interlocking electromagnet comprising an electromagnet and a movable member driven by the electromagnet, the making operation preventing device being so adapted that when the electromagnet is excited by a circuit opening instruction, the rotatable member is bent by the movable member to make the engagement with the releasing member impossible whereby the driving of the releasing member by the rotatable member can be prevented.
Thus, the rotatable member is bent to render the engagement of the rotatable member with the releasing member to be incapable to thereby prevent the rotatable member from driving the releasing member, whereby a needless circuit closing operation can be prevented when a circuit opening instruction is generated.
Further, the making operation preventing device prevents the plunger from moving.
Since the movement of the plunger is prevented to prevent the driving of the releasing member, a needless circuit closing operation can be prevented when a circuit opening instruction is generated.
Further, the making operation preventing device has an interlocking electromagnet comprising an electromagnet and a movable member driven by the electromagnet so that when the electromagnet is excited by a circuit opening instruction, the movement of the plunger is mechanically prevented by the movable member.
Since the movement of the plunger can mechanically be prevented by the movable member, the driving of the releasing member can be prevented. Accordingly, a needless circuit opening operation can be prevented when a circuit opening instruction is generated.
Further, the making operation preventing device has an interlocking coil which is excited by a circuit opening instruction to cancel an electromagnetic force of the circuit closing electromagnet whereby the movement of the plunger is prevented.
The movement of the plunger is prevented by canceling the electromagnet force of the circuit closing electromagnet, whereby a needless circuit closing operation can be prevented when a circuit opening instruction is generated.
Further, the making operation preventing device has an interlocking electromagnet comprising an electromagnet and a movable member driven by the electromagnet so that the electromagnet is excited by a circuit opening instruction and the movable member holds the releasing member so as not to move.
Since the releasing member is restricted so as not to being driven by the movable member, a needless circuit opening operation can be prevented when a circuit opening instruction is generated.
Further, an excitation breaking means is provided to stop excitation to the interlocking electromagnet or the interlocking coil when the circuit opening instruction is continued for a predetermined time.
Since the excitation to the interlocking electromagnet or the interlocking coil is stopped after the circuit opening instruction is continued for a predetermined time, the interlocking electromagnet or the interlocking coil can be of a type of short time.